Relative cent: Difference between revisions
Wikispaces>xenwolf **Imported revision 438151008 - Original comment: tried to improve the use for measuring the quality of JI approximations** |
Wikispaces>xenwolf **Imported revision 624715379 - Original comment: ** |
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<h2>IMPORTED REVISION FROM WIKISPACES</h2> | <h2>IMPORTED REVISION FROM WIKISPACES</h2> | ||
This is an imported revision from Wikispaces. The revision metadata is included below for reference:<br> | This is an imported revision from Wikispaces. The revision metadata is included below for reference:<br> | ||
: This revision was by author [[User:xenwolf|xenwolf]] and made on <tt> | : This revision was by author [[User:xenwolf|xenwolf]] and made on <tt>2018-01-11 03:34:16 UTC</tt>.<br> | ||
: The original revision id was <tt> | : The original revision id was <tt>624715379</tt>.<br> | ||
: The revision comment was: <tt> | : The revision comment was: <tt></tt><br> | ||
The revision contents are below, presented both in the original Wikispaces Wikitext format, and in HTML exactly as Wikispaces rendered it.<br> | The revision contents are below, presented both in the original Wikispaces Wikitext format, and in HTML exactly as Wikispaces rendered it.<br> | ||
<h4>Original Wikitext content:</h4> | <h4>Original Wikitext content:</h4> | ||
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Measuring the error of an approximation of an interval in an edo in terms of relative cents gives the relative error, which so long as the corresponding val is used is additive. For instance, the fifth of 12edo is 1.995 cents flat, or -1.955 cents sharp, which is therefore also its error in relative cents. The fifth of [[41edo]] is 1.654 relative cents sharp. Thus for 53=41+12, the fifth is -1.955 + 1.654 = -0.301 relative cents sharp, and hence (-0.301)*(12/53) = -0.068 cents sharp, which is to say 0.068 cents flat. | Measuring the error of an approximation of an interval in an edo in terms of relative cents gives the relative error, which so long as the corresponding val is used is additive. For instance, the fifth of 12edo is 1.995 cents flat, or -1.955 cents sharp, which is therefore also its error in relative cents. The fifth of [[41edo]] is 1.654 relative cents sharp. Thus for 53=41+12, the fifth is -1.955 + 1.654 = -0.301 relative cents sharp, and hence (-0.301)*(12/53) = -0.068 cents sharp, which is to say 0.068 cents flat. | ||
If you want to quantify the approximation of a given [[JI]] interval in a given [[equal|equal-stepped]] tonal system, you can consider the absolute distance of 50 r¢ as the worst possible and 0 r¢ as the best possible. For example, [[5edo]] has a relatively good approximated [[natural seventh]] with the ratio [[7_4|7/4]]: the absolute distance of 4\5 in 5edo is 8.826 ¢ or 3.677 r¢ flat of 7/4. But the approximations of its multiple edos [[10edo]] (7.355 r¢), [[15edo]] (11.032 r¢) ... become progressively worse (in a relative sense). So in [[65edo]], there is the 7/4 situated halfway between two adjacent pitches (off by at least 47.807 r¢), but its absolute distance from this interval in cents is still the same as for 5edo: 8.826 ¢ flat. | == Application for quantify approximation == | ||
If you want to quantify the approximation of a given [[JI]] interval in a given [[equal|equal-stepped]] tonal system, you can consider the absolute distance of 50 r¢ as the worst possible and 0 r¢ as the best possible. For example, [[5edo]] has a relatively good approximated [[natural seventh]] with the ratio [[7_4|7/4]]: the absolute distance of 4\5 in 5edo is 8.826 ¢ or 3.677 r¢ flat of 7/4. But the approximations of its multiple edos [[10edo]] (7.355 r¢), [[15edo]] (11.032 r¢) ... become progressively worse (in a relative sense). So in [[65edo]], there is the 7/4 situated halfway between two adjacent pitches (off by at least 47.807 r¢), but its absolute distance from this interval in cents is still the same as for 5edo: 8.826 ¢ flat. See [[Pepper ambiguity]] for a mathematical approach to quantify the approximations for sets of intervals. | |||
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Measuring the error of an approximation of an interval in an edo in terms of relative cents gives the relative error, which so long as the corresponding val is used is additive. For instance, the fifth of 12edo is 1.995 cents flat, or -1.955 cents sharp, which is therefore also its error in relative cents. The fifth of <a class="wiki_link" href="/41edo">41edo</a> is 1.654 relative cents sharp. Thus for 53=41+12, the fifth is -1.955 + 1.654 = -0.301 relative cents sharp, and hence (-0.301)*(12/53) = -0.068 cents sharp, which is to say 0.068 cents flat.<br /> | Measuring the error of an approximation of an interval in an edo in terms of relative cents gives the relative error, which so long as the corresponding val is used is additive. For instance, the fifth of 12edo is 1.995 cents flat, or -1.955 cents sharp, which is therefore also its error in relative cents. The fifth of <a class="wiki_link" href="/41edo">41edo</a> is 1.654 relative cents sharp. Thus for 53=41+12, the fifth is -1.955 + 1.654 = -0.301 relative cents sharp, and hence (-0.301)*(12/53) = -0.068 cents sharp, which is to say 0.068 cents flat.<br /> | ||
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If you want to quantify the approximation of a given <a class="wiki_link" href="/JI">JI</a> interval in a given <a class="wiki_link" href="/equal">equal-stepped</a> tonal system, you can consider the absolute distance of 50 r¢ as the worst possible and 0 r¢ as the best possible. For example, <a class="wiki_link" href="/5edo">5edo</a> has a relatively good approximated <a class="wiki_link" href="/natural%20seventh">natural seventh</a> with the ratio <a class="wiki_link" href="/7_4">7/4</a>: the absolute distance of 4\5 in 5edo is 8.826 ¢ or 3.677 r¢ flat of 7/4. But the approximations of its multiple edos <a class="wiki_link" href="/10edo">10edo</a> (7.355 r¢), <a class="wiki_link" href="/15edo">15edo</a> (11.032 r¢) ... become progressively worse (in a relative sense). So in <a class="wiki_link" href="/65edo">65edo</a>, there is the 7/4 situated halfway between two adjacent pitches (off by at least 47.807 r¢), but its absolute distance from this interval in cents is still the same as for 5edo: 8.826 ¢ flat.<br /> | <!-- ws:start:WikiTextHeadingRule:0:&lt;h2&gt; --><h2 id="toc0"><a name="x-Application for quantify approximation"></a><!-- ws:end:WikiTextHeadingRule:0 --> Application for quantify approximation </h2> | ||
If you want to quantify the approximation of a given <a class="wiki_link" href="/JI">JI</a> interval in a given <a class="wiki_link" href="/equal">equal-stepped</a> tonal system, you can consider the absolute distance of 50 r¢ as the worst possible and 0 r¢ as the best possible. For example, <a class="wiki_link" href="/5edo">5edo</a> has a relatively good approximated <a class="wiki_link" href="/natural%20seventh">natural seventh</a> with the ratio <a class="wiki_link" href="/7_4">7/4</a>: the absolute distance of 4\5 in 5edo is 8.826 ¢ or 3.677 r¢ flat of 7/4. But the approximations of its multiple edos <a class="wiki_link" href="/10edo">10edo</a> (7.355 r¢), <a class="wiki_link" href="/15edo">15edo</a> (11.032 r¢) ... become progressively worse (in a relative sense). So in <a class="wiki_link" href="/65edo">65edo</a>, there is the 7/4 situated halfway between two adjacent pitches (off by at least 47.807 r¢), but its absolute distance from this interval in cents is still the same as for 5edo: 8.826 ¢ flat. See <a class="wiki_link" href="/Pepper%20ambiguity">Pepper ambiguity</a> for a mathematical approach to quantify the approximations for sets of intervals.<br /> | |||
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<em>...also the term <a class="wiki_link" href="/centidegree">centidegree</a> was suggested, but this seems to be used already as a unit for temperature.</em></body></html></pre></div> | <em>...also the term <a class="wiki_link" href="/centidegree">centidegree</a> was suggested, but this seems to be used already as a unit for temperature.</em></body></html></pre></div> | ||